package week5;

public class Circle {
    private double radius;
    public Circle(double radius){
        this.radius=radius;
    }
    public double calculateArea(){
        return Math.PI*radius*radius;
    }
    public static void main(String[]args){
        Circle circle=new Circle(5);
        System.out.println("圆的面积为："+circle.calculateArea());
    }
}
